Adjusting device for a turbocharger, and turbocharger

Abstract

The invention relates to a control device for a turbocharger, comprising an exhaust gas conducting section through which fluid can flow and which includes a bypass duct for bypassing a turbine wheel that is rotatably arranged in the exhaust gas conducting section, and comprising an adjusting arm (3) for accommodating a valve element (2) provided for opening or blocking a flow cross-section of the bypass duct; the adjusting arm (3) is movably accommodated in the exhaust gas conducting section; furthermore, a flexible element (14) is provided at least for securing the valve element (2) in place on the adjusting arm (3). According to the invention, the flexible element (14) is designed so as to be radially slidable in order to reduce adjustment forces.

Claims

1. A control device for an exhaust turbocharger, the exhaust turbocharger having an exhaust gas conducting section, through which fluid can flow and which comprises a bypass duct for bypassing a turbine wheel rotatably disposed in the exhaust gas conducting section, the control device comprising: a valve element which is provided for opening or closing a flow cross-section of the bypass duct, an adjusting arm accommodating the valve element, wherein the adjusting arm is movably accommodated in the exhaust gas conducting section, a spring element at least for securing the valve element in place on the adjusting arm, and a cover disc, wherein the spring element is accommodated between the cover disc and the adjusting arm, and wherein the spring element can slide radially in order to reduce adjusting forces, and wherein the cover disc comprises a groove on its cover surface facing the spring element, and wherein the groove has an arcuate cross-sectional surface having a groove radius, and wherein an outer portion of the spring element is downwardly bent having a bent radius which matches the groove radius.

2. The control device as claimed in claim 1, wherein the spring element can slide about a tilt point of the valve element.

3. The control device as claimed in claim 1, wherein the cover disc is designed to support the radially sliding movement of the spring element.

4. The control device as claimed in claim 1, wherein a second contact surface of the spring element, which has a smaller diameter than an outer edge of the spring element, has contact with the adjusting arm and wherein, between the outer edge and the adjusting arm a further space is formed.

5. An exhaust turbocharger, comprising the turbine wheel and the control device as in claim 1.

6. The control device as in claim 1, wherein the groove is inwardly and outwardly delimited in the cover disc.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a perspective view of a control device of an exhaust turbocharger according to the prior art.

(3) FIG. 2 is a perspective cross-sectional view of the control device of FIG. 1.

(4) FIG. 3 is a section of a longitudinal cross-section of the control device of FIG. 1.

(5) FIG. 4 is a perspective view of a control device in accordance with the invention of an exhaust turbocharger in accordance with the invention.

(6) FIG. 5 is a perspective cross-sectional view of the control device of FIG. 4.

(7) FIG. 6 is a section of a longitudinal cross-section of the control device of FIG. 4.

DETAILED DESCRIPTION

(8) A control device 1 of an exhaust turbocharger, not illustrated in more detail, according to the prior art is designed as illustrated in FIG. 1. The exhaust turbocharger comprises an exhaust gas conducting section, through which fluid can flow and which is not illustrated in more detail, said exhaust gas conducting section having a fluid, generally exhaust gas, flowing through it during operation of the exhaust turbocharger. The exhaust gas is generally a combustion product of an internal combustion engine, not illustrated in more detail. Such control devices are known as wastegate devices.

(9) The exhaust turbocharger is allocated an air conducting section, through which fluid can flow and which is not illustrated in more detail, and a bearing section which is positioned between the exhaust gas conducting section and the air conducting section and is not illustrated in more detail, wherein a rotor assembly, not illustrated in more detail, is rotatably accommodated in the bearing section. The rotor assembly comprises a compressor wheel, not illustrated in more detail, and a turbine wheel, not illustrated in more detail, these being connected to one another for conjoint rotation by means of a shaft, not illustrated in more detail. The compressor wheel is rotatably accommodated in a first wheel chamber, not illustrated in more detail, of the air conducting section in order to take in generally fresh air, and the turbine wheel is rotatably accommodated in a second wheel chamber, not illustrated in more detail, of the exhaust gas conducting section. When the exhaust turbocharger is in operation, the turbine wheel is subjected to, and driven by, the exhaust gas flowing through the exhaust gas conducting section, wherein a rotational movement can be effected. This rotational movement can be transferred to the compressor wheel with the aid of the shaft, which compressor wheel can therefore effect a rotational movement simultaneously with the rotational movement of the turbine wheel. With the aid of the compressor wheel and the rotational movement thereof, fresh air is taken in and is compressed in the air conducting section.

(10) The exhaust turbocharger is designed as a so-called wastegate charger, i.e. it comprises the control device 1 for complete or partial bypassing of the turbine wheel with the aid of a bypass duct, not illustrated in more detail, formed in the exhaust gas conducting section. This control device 1, which is designed to control a flow cross-section, not illustrated in more detail, of the bypass duct, comprises a valve element 2, designed to be able to close and open said duct, preferably in the form of a flap, generally designated as a wastegate flap or wastegate valve, and an adjusting device, not illustrated in more detail, for actuating this valve element 2.

(11) The valve element 2, comprising a valve element longitudinal axis 25, is disposed on an adjusting arm 3 of the adjusting device. The adjusting arm 3 comprises, on its end 5 remote from an adjusting shaft 4 of the adjusting arm 3, a forked accommodating opening 6 for accommodating a securing pin 7.

(12) The securing pin 7 serves to prevent rotation of the valve element 2 which is accommodated in a further accommodating opening 8 of the adjusting arm 3 with the aid of a pin-shaped or bolt-shaped spigot 9. The spigot 9 and the securing pin 7 are formed on a first valve surface 10 facing the adjusting arm 3. A second valve surface 11 of the valve element 2 remote from the first valve surface 10 is positioned facing the flow cross-section to be controlled.

(13) The valve element 2 is fixed with the aid of a cover disc 12 on the adjusting arm 3. The spigot 9 protrudes through the further accommodating opening 8 and into the cover disc 12. On its spigot end 13 remote from the second valve surface 11 it is connected in a rivet-like manner to the adjusting arm 3 with the aid of the cover disc 12. It can likewise also be welded, or welded and riveted.

(14) A spring element 14 for tensioning the valve element 2 is disposed between the adjusting arm 3 and the cover disc 12, whereby rattling noises during movement of the valve element 2 are reduced. Furthermore, this spring element 14 serves to compensate for play, in particular even play compensation owing to large changes in temperature during operation of the exhaust turbocharger. In this way wear between the adjusting arm 3, the valve element 2 and the cover disc 12 is reduced.

(15) The spring element 14 is designed as a plate spring and comprises an inner diameter DI and an outer diameter DA. In the region of the inner diameter DI a first contact surface 15 is formed which is on a level with the adjusting arm 3. In other words, the first contact surface 15 lies flat against the adjusting arm 3. In the region of the outer diameter DA a second contact surface 16 is formed which is on a level with the cover disc 12. In other words, the second contact surface 16 is supported flat against the cover disc 12.

(16) When the control device 1 is in operation, the valve element 2 rotates or pivots about an axis of rotation 17 of the adjusting shaft 4. A so-called tilt point 18 of the valve element 2 is thus formed, about which it tilts owing to decentralised loading. This leads to additional loading of the spring element 14, from which a high level of setting forces results. These setting forces are to be applied by the actuator, not illustrated in more detail, which effects an adjustment of the valve element 2.

(17) FIGS. 4 to 6 illustrate a control device 1 in accordance with the invention. The control device 1 in accordance with the invention comprises the spring element 14 which is formed in such a way that the spring element 14 can effect a radially sliding movement along the arrow 19 during operation of the exhaust turbocharger.

(18) The spring element 14 comprises the first contact surface 15 in the region of its inner diameter DI. On its outer diameter DA, the spring element 14 is arcuate, wherein a spring element radius RF is formed on the outer diameter DA. The first contact surface 15, which is on a level with the adjusting arm 3, serves during mounting to centre the spring element 14.

(19) The cover disc 12 comprises a groove 21 on its cover surface 20 facing the spring element 14, which groove has an arcuate cross-sectional surface 24. The cross-sectional surface 24 comprises a cover disc radius RD in a movement region 22 adjoining the cover surface 20, which cover disc radius corresponds to a space A between the tilt point 18 and an outer edge 23 of the spring element 14.

(20) With the aid of the spring element radius RF the second contact surface 16 is formed in a quasi-linear manner since the outer edge 23 does not lie against the adjusting arm 3 and a further space 26 is formed between the outer edge 23 and the adjusting arm 3.

(21) During operation of the control device 1 the spring element 14 can carry out a rotation about the tilt point 18, whereby the spring element 14 is relieved. In other words, this means that the spring element 14 can slide in the groove 21 about the tilt point 18 of the valve element 2 with the aid of its arcuate outer edge 23. The cover disc 12 is designed to support the radially sliding movement of the spring element 14.